Seals of diverse materials and shapes are evidenced by the prior U.S. Pat. No. 1,888,957 to Longenecker issued Nov. 22, 1932, flexible rubber diaphragm in a mortar mixer; Phillips (U.S. Pat. No. 2,452,144, issued Oct. 26, 1948), synthetic rubber in an electrical swing joint; Malone (U.S. Pat. No. 2,990,220, issued June 27, 1961), paired seals with metallic spacer rings and bearing retainers; Cotchett (U.S. Pat. No. 2,991,514, issued July 11, 1961), having felt and nylon washers distorted into cup shape; Tamm (U.S. Pat. No. 3,112,417, issued Nov. 26, 1963), having acrylonitrile rubber, in an electric motor, "stable in the presence of lubricant"; Bilocq (U.S. Pat. No. 3,420,590, issued Jan. 7, 1969), alternating metallic and "Teflon" seals for an idler roller; and Vincent (U.S. Pat. No. 3,450,392, issued June 17, 1969), having split, angular, compressible, packing rings.